創建web項目 實現的效果！ 用戶點擊頁面不同的鏈接，后台調用不同的代碼！
創建兩個類實現共同的接口！
public interface Action {
String execute();
}
public class LoginAction implements Action{
public String execute(){
System.out.println("LoginAction......");
return "success";
}
}
public class ListAction implements Action {
public String execute(){
System.out.println("ListAction......");
return "success";
}
}
想讓用戶能訪問到我們的后台代碼，要么使用servlet 要么使用filter!
使用filter
創建一個filter用來攔截用戶的請求
public class DoFilter implements Filter {
//全局的變量
Map<String,String> map=new HashMap<String, String>();
//初始化操作
@Override
public void init(FilterConfig arg0) throws ServletException {
System.out.println("DoFilter 初始化了.............................");
// key是用戶請求的路徑 value 是對應的全類名
map.put("/login","cn.bdqn.action.LoginAction");
map.put("/list","cn.bdqn.action.ListAction");
}
//真正的處理
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
//向下轉型
HttpServletRequest httpServletRequest=(HttpServletRequest) request;
HttpServletResponse httpServletResponse=(HttpServletResponse) response;
//看一下 各個路徑的區別
System.out.println("getContextPath()==>"+httpServletRequest.getContextPath());//項目名
System.out.println("getServletPath()==>"+httpServletRequest.getServletPath());//訪問的路徑
System.out.println("getRequestURI()==>"+httpServletRequest.getRequestURI());//項目下面的路徑
System.out.println("getRequestURL()==>"+httpServletRequest.getRequestURL());//帶協議的完整路徑
//應該使用getServletPath
String path=httpServletRequest.getServletPath();
try {
if (path.equals("/index.jsp")) {
chain.doFilter(request, response); //放行
}else{
Action action=(Action) Class.forName(map.get(path)).newInstance();
action.execute();
//跳轉到成功界面
httpServletRequest.getRequestDispatcher("/success.jsp").forward(request, response);
}
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
@Override
public void destroy() {
}
}
前台頁面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<a href="login">登錄 </a>
<a href="list">詳情 </a>
</body>
</html>
sucess.jsp頁面就是一個成功界面！！！省略掉！
我們使用xml文件來代替 map中 所保存的 鍵值對 信息！
key：用戶的請求
value:對應的后台實現類 全類名！
